This invention relates in general to catheters, and more particularly to a retention catheter as is commonly used in the practice of medicine, particularly in urology.
As is well known in the medical arts, a catheter used in urology typically has a flexible tube that is introduced through the urinary duct to reach the vesica, or in certain cases, the kidneys for the purpose of draining urine or other fluid therefrom.
Such catheters require means, typically in the form of inflatable members, that are effective to securely and firmly provide a safety-fixing of the catheter in an established drainage position throughout the period of its use. Without such safety-fixing provisions, there is a danger of the catheter tube dislocating from its intended drainage position, and unthreading through the insertion duct of the patient.
Until the present, several techniques have been developed in catheter construction to achieve retention of the catheter tube at the desired drainage location, but these various techniques have in one way or another presented certain problems.
Some of these problems arose in connection with catheters used with male patients wherein the urinary ducts are less accessible than female patients.
It has been found generally that the retention member or members provided for a catheter, in order to firmly fix the drainage position thereof, must be adjustable in size from a minimum size permitting the catheter to be introduced into the inlet duct of the organ to be drained, up to a retention configuration size that is necessarily larger than that of the inlet duct.
In the case of any catheter, whatever retention member or members are used, there has to be assured drainage at the most declining, or deepest point.
In some types of prior art catheters, a bulb type retention member was applied to the insertion end of the catheter, and such bulb did give some interference with draining the body cavity at the most declining portion thereof, because of an inappropriate location of the drainage hole in the catheter tube in relation to the retention bulb.
In certain other types of retention catheters, satisfactory drainage has been achieved, but in order to achieve such desired results, it was necessary to use complex means and procedures for adjusting the size of the retention member for a better location in situ of the catheter.
Catheters inserted into a patient eventually have to be removed, and in a case of certain prior art retention catheters, it was difficult to achieve a sufficient size reduction of the retention member as would allow unthreading of the catheter without damage to the urinary duct.